1. Field of the Invention
The present invention relates to a compressor with a capacity modulation system and, more particularly, to a rotary compressor with a capacity modulation system utilizing a re-expansion chamber.
2. Description of the Related Art
Capacity modulation of compressors is known in the art. In a capacity modulated compressor, the output is varied in proportion to the demand placed on it. In refrigeration systems and in heating, ventilation, and air conditioning (HVAC) systems with compressors, capacity modulation is used to reduce energy consumption and increase system reliability. These systems also use capacity modulated compressors to more precisely control environmental parameters in the conditioned space, such as temperature, humidity, air flow noise, and equipment noise.
A conventional technique for modulating the capacity of a compressor, in particular a rotary compressor, involves controlling the speed of the compressor motor using a variable speed inverter.
There are a number of problems associated with conventional capacity modulation systems. Variable speed inverters are expensive and unreliable. These inverters rely on complex electronics that are costly to produce and prone to failure. Further, due to the complexity of inverter-driven compressor systems, highly trained technicians are required to service them.
To overcome the drawbacks of the prior art and in accordance with the purpose of the invention, as embodied and broadly described herein, one aspect of the invention provides a rotary compressor including a compression chamber, a suction port for providing fluid at a suction pressure to the compression chamber, a roller within the compression chamber for compressing fluid in the compression chamber, and a discharge port for removing fluid at a discharge pressure from the compression chamber. The compressor further includes a re-expansion chamber and a re-expansion port positioned between the suction port and the discharge port. The re-expansion port provides a flow path between the compression chamber and the re-expansion chamber. A valve device associated with the re-expansion port allows or prevents fluid communication between the compression chamber and the re-expansion chamber.
In another aspect, the invention provides a rotary compressor, including a compression chamber, a rotatable shaft disposed within the compression chamber, and a roller disposed on the shaft in contact with a wall of the compression chamber. A partition contacts the wall of the compression chamber and the roller, the partition defining a low pressure portion and a high pressure portion within the compression chamber. A suction channel is in fluid communication with the low pressure portion for providing fluid to the compression chamber at a suction pressure and a discharge channel is in fluid communication with the high pressure portion for removing fluid from the compression chamber at a discharge pressure. The compressor further includes a re-expansion port in the wall of the compression chamber and a re-expansion chamber connected to the re-expansion port.
In a further aspect, the invention provides a rotary compressor with a capacity modulation system, the compressor including a substantially cylindrical compression chamber, a rotatable shaft disposed within the compression chamber, a roller eccentrically disposed on the shaft in contact with a wall of the compression chamber, and a vane disposed between the wall of the compression chamber and the roller, the vane defining a low pressure portion and a high pressure portion within the compression chamber. A suction channel is in fluid communication with the low pressure portion for providing fluid to the compression chamber at a suction pressure and a discharge channel is in fluid communication with the high pressure portion for removing fluid from the compression chamber at a discharge pressure. A re-expansion channel is adjacent to the compression chamber, the re-expansion channel having an end forming a re-expansion port in the wall of the compression chamber. A re-expansion chamber is connected to the re-expansion channel. The compressor further includes a valve disposed in the re-expansion channel movable between a first position, in which the valve allows fluid communication between the compression chamber and the re-expansion chamber, and a second position, in which the valve prevents fluid communication between the compression chamber and the re-expansion chamber.
In yet another aspect, the invention provides a method of modulating the capacity of a rotary or swing link compressor including a compression chamber and a rotary compressing member in the compression chamber. The method includes supplying fluid to the compression chamber through an inlet port, providing the compressor with a re-expansion chamber, and providing a flow path between the compression chamber and the re-expansion chamber. The flow path is positioned at a location spaced from the inlet port. The method further includes operating the compressor in a reduced capacity mode, including opening the flow path, compressing fluid in the compression chamber and the re-expansion chamber, withdrawing compressed fluid from the compression chamber through a discharge port, and allowing compressed fluid in the re-expansion chamber to return to the compression chamber. The method further includes supplying additional fluid to the compression chamber through the inlet port and operating the compressor in a full capacity mode, including closing the flow path, compressing the fluid in the compression chamber, and withdrawing the compressed fluid from the compression chamber through the discharge port.
Additional advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.